When transferring a liquid substance from a vessel, for example a vial, by means of an injection needle, or when adding a liquid to a dry substance for dissolving this and when further transferring the substance to the intended use, e.g. injection to a patient's blood vessel or to an infusion bottle or the like, one cannot avoid that the injection needle, by which the liquid substance is removed from the vial, gives off aerosols and drops to the environment or that the persons handling the injection needle get contaminated. Especially in cases where the substance consists of cytotoxic drugs, radio-labelled or allergy-inducing substances it is for safety reasons important that the transfer of such substances from the vial to a patient, possibly by way of an infusion bag, takes place under satisfactory conditions and also so that an air contamination imparted by the injection needle during the transfer is avoided.
One example of a connector device used for the above mentioned purposes is disclosed in the publication of US 2003070726, in which an improved fluid transfer assembly comprising a bottle connector and a drug bottle is disclosed. The bottle connector comprises a neck element to which an injector can be fixedly coupled, and second connection means to connect the bottle connector to the drug bottle. The connector has a hollow needle to penetrate a closure on the bottle. A fluid transfer channel is arranged within the hollow needle. The bottle connector further comprises a pressure compensating means comprising a flexible container and a gas channel within the hollow needle for transporting gas from the bottle to the flexible container or vice versa in order to allow fluid to be transferred via the fluid transfer channel. The gas channel includes a filter to prevent liquid passage into said flexible container as this may damage the flexible container.
The above mentioned connector has some drawbacks, one drawback is that the filter can be blocked. If the filter is blocked, the function of the flexible container is reduced and the pressure inside the bottle can instantly increase or decrease to levels which could cause difficulties with respect to handling. As mentioned above when dealing with cytotoxic drugs, radio-labelled or allergy-inducing substances, pressure increases or decreases inside the bottle can be hazardous, since in theory, it could lead to an increased risk of leakage. It therefore seems to be a need for additional improvements in this field.
Another connector, in this case a vial adaptor, is disclosed in the patent application US 2007/0106244 A1. The vial adaptor has a housing, an expandable chamber, a filter to prevent fluid from entering the expandable chamber. A check valve is arranged in the proximity of the filter to enable a one way fluid flow. The connector is however not very flexible in terms of handling nor does it provide any means by which the filter can be prevented form being obstructed, i.e. clogged. The teaching of the publication is further that it is preferable that the check valve has as low cracking pressure as possible.